The present invention relates to a fuel injection pump for internal combustion engines, of the type in which the rate of fuel delivery is adjusted by rotating a plunger within a plunger barrel. More particularly, the invention is concerned with an improvement in the device for rotating the plunger in the fuel injection pump of the type mentioned above.
A fuel injection pump called "Bosch" type fuel injection pump has been known. This fuel injection pump has a plunger adapted to be moved reciprocatingly in a plunger barrel (referred to simply as "barrel", hereinafter) to pressurize and deliver a fuel. The rate of delivery of the fuel is adjusted by changing the timing at which the fuel pressurizing chamber in the barrel is brought into communication with a fuel relief port formed in the wall of the barrel, through changing the relative rotational position relatively to each other. In this fuel injection pump, in order to cause the rotation of the plunger, there is provided a plunger rotating member which engaged in the circumferential direction with a projection provided at an intermediate portion of the plunger, and a rack gear disposed at one side of the plunger rotating member and meshing with the gear teeth formed on the outer periphery of the plunger rotating member. In operation, the rack gear is pulled and pushed to rotate the plunger rotating member, thereby to cause the rotation of the plunger.
Thus, this known fuel injection pump requires a combination of a plunger rotating member and a rack for rotating the plunger, resulting in a complicated construction and uneconomically raised cost of production of the fuel injection pump.